The hexagram and line statements (the Zhou Yi proper) date to the Western Zhou, roughly 9th-8th centuries BCE, with traditional attribution to King Wen and the Duke of Zhou. The Ten Wings, including the Xici zhuan and Xiang zhuan, are Warring States to early Han commentarial layers that reframed the oracle as cosmology and ethics. The Shanghai Museum bamboo manuscripts (c. 300 BCE) contain the oldest excavated copy of the Zhou Yi text.
Popular accounts credit the I Ching to the culture hero Fu Xi inventing trigrams in deep antiquity, a myth recorded already in the Xici zhuan itself. The excavated manuscript tradition supports the Western Zhou dating, not the legendary one.
The Wings performed the great reversal: a text that answered questions became a text that reads the questioner. By the time the Xici calls the Changes a mirror of all under heaven, divination has quietly become self-examination, the transformation Jung would formalize two millennia later.
If the oldest layer of the Changes is a court diviner's ledger, what else began as a record of questions?